The present invention relates to a color filter and a color image sensor using the same.
A recently developed color printer reproduces a well-balanced color print by classifying a color original (such as a color negative film) into a plurality of scenes and regulating the degree of insertion of a color correction filter into an optical path of each scene. To classify a color original into plural scenes, a color image sensor has been used to measure three color densities of the color original at each point of measurement thereon.
To read a color original, either a three-image type scanner or a single-image type sensor is used. With the former, three colors are separately measured by disposing three color filters, e.g. blue, green and red, at the light-receiving surface of each image sensor. With the latter method, a color filter with a mosaic pattern of blue color area, green color area and red color area is disposed at the receiving surface of the image sensor, which is cost effective.
With the latter single-image type color image sensor, three color signals for each pixel are mixed and collected by the scanner. Thus, the signal processing, such as color correction, becomes complicated, and it become necessary to separate the three colors for storing the respective three color signals in a memory. Furthermore, it is desirable to set a different charge storage time for each color based on incident light to broaden the dynamic range of the color image sensor and to obtain a signal with low noise.
To read a color signal independently for each color using a MOS type color image sensor, it is necessary to provide horizontal and vertical signal lines for each color. However, in a conventional color image sensor, there is used a color filter whose color areas of the same color are not disposed in contact relation to each other, so that three horizontal and three vertical signal lines must be provided to surround each photoelectric conversion cell. This results in complicated wiring and a limited light-receiving area for photoelectric conversion cells because of the wiring space needed, thereby limiting the aperture and hence the sensitivity.